#include<iostream>
using namespace std;
const int N = 5e3 + 10;
int a[N][N],f[N][N];
int main()
{
	int n , m;
	cin >> n >> m;
	for(int i = 1; i <= n; i++)
	{
		int x , y , v;
		cin >> x >> y >> v;
		x++ , y++;
		a[x][y] += v;
	}
	n = 5001;
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j <= n; j++)
		{
			f[i][j] = f[i - 1][j] + f[i][j - 1] - f[i - 1][j - 1] + a[i][j];
		}
	}
	
	int ret = 0;
	m = min(m,n);
	for(int x2 = m; x2 <= n; x2++)
	{
		for(int y2 = m; y2 <= n; y2++)
		{
			int x1 = x2 - m + 1, y1 = y2 - m + 1;
			ret = max(ret, f[x2][y2] - f[x1 - 1][y2] - f[x2][y1 - 1] + f[x1 - 1][y1 - 1]);
		}
	}
	cout << ret << endl;
	return 0;
} 
